Turbine engine fan case with tip injection air recirculation passage

ABSTRACT

A fan case assembly adapted for use with a gas turbine engine includes a fan track liner and an annular case. The fan track liner extends circumferentially at least partway about a central axis of the gas turbine engine. The annular case is configured to support the fan track liner at a radial position relative to the central axis. The fan case assembly further includes an air recirculation duct configured to redirect air around the fan track liner.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Embodiments of the present disclosure were made with government supportunder Contract No. FA865019F2078. The government may have certainrights.

FIELD OF THE DISCLOSURE

The present disclosure relates generally to gas turbine engines, andmore specifically to fan containment cases for gas turbine engines.

BACKGROUND

Gas turbine engines used in aircraft often include a fan assembly thatis driven by an engine core to push air through the engine and providethrust for the aircraft. A typical fan assembly includes a fan rotorhaving blades and a fan case that extends around the blades of the fanrotor. During operation, the fan blades of the fan rotor are rotated topush air through the engine. The fan case both guides the air pushed bythe fan blades and provides a protective band that blocks fan bladesfrom escaping out of the fan assembly in case of a blade-off event inwhich a fan blade is released from the fan rotor.

Fan cases sometimes include metallic shrouds and liners positionedbetween the metallic shroud and the fan blades. Liners may be coupled tometallic shrouds by hanger features that extend from the metallicshrouds, by adhesives that provide a permanent bond to the metallicshrouds, or by fasteners/through bolts bolted directly to the case. Fancases may also provide containment functions in case of a blade-offevent. The containment function of the fan cases may make it difficultto incorporate other features into the fan case, while still maintainingthe structural integrity of the fan case system.

SUMMARY

The present disclosure may comprise one or more of the followingfeatures and combinations thereof.

A fan case assembly adapted for use with a gas turbine engine mayinclude a fan track liner, an annular case, and an air recirculationduct. The fan track liner may extend circumferentially at least partwayabout a central axis of the gas turbine engine. The annular case may beconfigured to support the fan track liner at a radial position relativeto the central axis. The air recirculation duct may be configured todirect a portion of gases flowing through a gas path of the gas turbineengine from an aft end of the fan track liner into the gas path axiallyforward of a forward end of the fan track liner.

In some embodiments, the fan track liner may include a forward end, anaft end, and an inner radial surface. The aft end may be spaced apartaxially from the forward end. The inner radial surface may extendbetween the forward end and the aft end to define the gas path of thegas turbine engine.

In some embodiments, the annular case may include an outer wall and ahook. The outer wall may extend circumferentially around the centralaxis of the gas turbine engine. The hook may extend radially inward fromthe outer wall to support the forward end of the fan track liner.

In some embodiments, the air recirculation includes an extraction portin fluid communication with the gas path of the gas turbine engine, aconduit in fluid communication with the extraction port, and aninjection port in fluid communication with the gas path of the gasturbine engine and the conduit. The extraction port may extend radiallythrough the outer wall at a location axially aft of the aft end of thefan track liner. The conduit may extend axially forward from theextraction port toward the forward end of the fan track liner. Theconduit may be located radially outward of the outer wall. The injectionport may extend radially inward from the conduit through the outer wallat a location axially forward of the forward end of the fan track linerand the hook of the annular case.

In some embodiments, the annular case may further include a flange. Theflange may extend radially outward from the outer wall axially aft ofthe hook. The extraction port of the air recirculation duct may extendthrough the outer wall axially aft of the flange.

In some embodiments, the conduit of the air recirculation duct may belocated radially outward of the flange of the annular case. The flangeof the annular case may engage the conduit to support the airrecirculation duct relative to the annular case.

In some embodiments, the conduit may have a forward end and an aft end.The aft end may be spaced apart axially from the forward end.

In some embodiments, the conduit may have a first cross-section at theforward and aft ends of the conduit and a second cross-section at alocation axially between the forward and aft ends of the conduit. Thesecond cross-section may be different than the first cross-section.

In some embodiments, the injection port may extend radially inward andaxially aft. The injection port may extend radially inward and axiallyaft so that the injection port extends at an angle relative to a radialaxis that extends radially relative to the central axis.

In some embodiments, the conduit of the air recirculation duct mayextend through a passage formed in the flange of the annular case. Theconduit may extend through the passage so that the flange supports theair recirculation duct radially relative to the annular case.

In some embodiments, the annular case may further include a flange. Theflange may extend radially outward from the outer wall axially aft ofthe hook. The extraction port of the air recirculation duct may extendthrough the outer wall axially forward of the flange. In someembodiments, the extraction port may extend radially inward and axiallyaft.

In some embodiments, the extraction port may have a first section and anopening end. The first section may extend from the conduit. The openingend may extend from the first section.

In some embodiments, the opening end of the extraction port may form anopening. The opening may have a first area and the first section mayhave a second area. The second area may be smaller than the first area.

In some embodiments, the fan case assembly may further include a valve.The valve may be coupled to the extraction port of the air recirculationduct. The valve may be configured to vary a flow of gases through theextraction port.

In some embodiments, the valve may be configured to change between aclosed position and an open position. In the closed position, the valvemay block an opening of the extraction port to prevent the flow of gasesthrough the extraction port. In the open position, the valve may bespaced apart from the opening of the extraction port and a portion ofthe valve extends into the gas path to direct a portion of the flow ofgases flowing through the gas path toward the opening of the extractionport.

According to another aspect of the disclosure, a fan case assemblyadapted for use in a gas turbine engine may include a fan track liner,an annular case, and air recirculation duct. The fan track liner mayextend circumferentially at least partway about a central axis of thegas turbine engine. The annular case may be coupled with the fan trackliner to support the fan track liner radially in the gas turbine engine.The air recirculation duct may include an extraction port in fluidcommunication with the gas path of the gas turbine engine, a conduit,and an injection port in fluid communication with the gas path of thegas turbine engine.

In some embodiments, the fan track liner may include a forward end, anaft end, and an inner radial surface. The aft end may be spaced apartaxially from the forward end. The inner radial surface may extendbetween the forward end and the aft end to define a gas path of the gasturbine engine.

In some embodiments, the extraction port may extend radially through theannular case at a location axially aft of the aft end of the fan trackliner. The conduit may extend axially from the extraction port radiallyoutward of the annular case. The injection port may extend radially fromthe conduit through the annular case at a location axially forward ofthe forward end of the fan track liner.

In some embodiments, the annular case may include an outer wall, a hook,and a flange. The outer wall may extend circumferentially around thecentral axis of the gas turbine engine. The hook may extend radiallyinward from the outer wall. The flange may extend radially outward fromthe outer wall axially aft of the hook.

In some embodiments, the extraction port of the air recirculation ductmay extend through the outer wall axially aft of the flange. In someembodiments, the extraction port of the air recirculation duct mayextend through the outer wall axially forward of the flange.

In some embodiments, the conduit of the air recirculation duct may belocated radially outward of the flange of the annular case. The flangeof the annular case may engage the conduit. In some embodiments, theconduit of the air recirculation duct may extend through the flange ofthe annular case.

In some embodiments, the fan case assembly may further include a valve.The valve may be coupled to the extraction port of the air recirculationduct. The valve may be configured to vary a flow of gases through theextraction port.

According to another aspect of the disclosure, a method may includeproviding an annular case, a fan track liner, and an air recirculationduct. The annular case may extend around a central axis. The fan trackliner may extend circumferentially at least partway about the centralaxis. The air recirculation duct may include an extraction port, aninjection port, and a conduit that extends between and interconnects theextraction port and the injection port.

In some embodiments, the method may further include coupling the fantrack liner to the annular case. In some embodiments, the method mayfurther include extending the extraction port radially inward throughthe annular case axially aft of an aft end of the fan track liner. Insome embodiments, the method may further include extending the injectionport radially inward through the annular case axially forward of aforward end of the fan track liner so that the conduit is locatedradially outward of the annular case.

In some embodiments, the annular case may include an outer wall, a hook,and a flange. The outer wall may extend circumferentially. The hook mayextend radially inward from the outer wall. The flange may extendradially outward from the outer wall axially aft of the hook.

In some embodiments, the extraction port of the air recirculation ductmay extend through the outer wall axially aft of the flange. In someembodiments, the extraction port of the air recirculation duct mayextend through the outer wall axially forward of the flange.

These and other features of the present disclosure will become moreapparent from the following description of the illustrative embodiments.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cutaway view of a gas turbine engine that includes a fan, acompressor, a combustor, and a turbine, the fan including a fan rotorconfigured to rotate about an axis of the engine and a fan case assemblythat surrounds fan blades included in the fan rotor and showing that thefan case assembly includes an annular case, a fan track liner which maybe formed by a number of liner segments positioned around the fanblades, and a plurality of air recirculation ducts located radiallyoutward of the annular case;

FIG. 2 is an enlarged view of the fan case assembly of FIG. 1 showingthe air recirculation duct included in the fan case assembly isconfigured to direct a portion of gases flowing through the gas path ofthe gas turbine engine from an aft end of the fan track liner into thegas path axially forward of a forward end of the fan track liner;

FIG. 3 is a section view of the annular case included in the fan caseassembly of FIG. 1 showing the annular case includes an outer wall thatextends circumferentially around the axis of the gas turbine engine, ahook that extends radially inward from the outer wall to support theforward end of the fan track liner, and a flange that extends radiallyoutward from the outer wall axially aft of the hook, and further showingzones on the annular case that the air recirculation duct may extendthrough;

FIG. 4 is an enlarged view of FIG. 2 showing the air recirculation ductincludes an extraction port in fluid communication with the gas paththat extends radially through the outer wall at a location axially aftof the aft end of the fan track liner, an injection port in fluidcommunication with the gas path that extends radially through the outerwall at a location axially forward of the hook of the annular case, anda conduit that extends between and interconnects the extraction port andthe injection port at a location radially outward of the outer wall, andfurther showing the extraction port extends through the outer wallaxially aft of the flange so that the flange supports the conduit;

FIG. 4A is a detail view of FIG. 4 showing the extraction port with avalve coupled to an opening end of the extraction port that isconfigured to vary a flow of gases through the extraction port tocontrol the flow of gases through the air recirculation duct;

FIG. 5 is another embodiment of a fan case assembly for the gas turbineengine of FIG. 1 showing the fan case assembly includes an annular case,a fan track liner coupled to the case, and an air recirculation ductthat includes an extraction port, an injection port, and a conduit thatextends between and interconnects the extraction port and the injectionport at a location radially outward of the outer wall, and furthershowing the angle of the injection port is sharp to cause the injectionport to open closer to a hook of the annular case;

FIG. 6 is another embodiment of a fan case assembly for the gas turbineengine of FIG. 1 showing the fan case assembly includes an annular case,a fan track liner coupled to the case, and an air recirculation ductthat includes an extraction port, an injection port, and a conduit thatextends between and interconnects the extraction port and the injectionport at a location radially outward of the outer wall, and furthershowing the conduit has a varying cross-section moving axially aft fromthe injection port to the extraction port to allow a preferred areachange and/or to manage the packaging of the duct in the fan caseassembly;

FIG. 7 is another embodiment of a fan case assembly for the gas turbineengine of FIG. 1 showing the fan case assembly includes an annular case,a fan track liner coupled to the case, and an air recirculation ductthat includes an extraction port, an injection port, and a conduit thatextends between and interconnects the extraction port and the injectionport at a location radially outward of the outer wall, and furthershowing the extraction port extends through the outer wall at a locationaxially forward of the flange of the annular case;

FIG. 8 is another embodiment of a fan case assembly for the gas turbineengine of FIG. 1 showing the fan case assembly includes an annular case,a fan track liner coupled to the case, and an air recirculation ductthat includes an extraction port, an injection port, and a conduit thatextends between and interconnects the extraction port and the injectionport at a location radially outward of the outer wall, and furthershowing the fan case defines a portion of the gas path axially forwardand aft of the fan track liner and the extraction port has an openingend that flares out so that the opening has a larger area than the restof the air recirculation duct;

FIG. 9 is another embodiment of a fan case assembly for the gas turbineengine of FIG. 1 showing the fan case assembly includes an annular case,a fan track liner coupled to the case, and an air recirculation ductthat includes an extraction port, an injection port, and a conduit thatextends between and interconnects the extraction port and the injectionport at a location radially outward of the outer wall, and furthershowing the fan case defines a portion of the gas path axially forwardand aft of the fan track liner and the conduit extends through a flangeof the annular case;

FIG. 10 is an elevation of the view of the fan case assembly of FIG. 2looking radially inward from radially outward of the fan case assemblyshowing the air recirculation duct only extends axially such that theextraction port is circumferentially aligned with the injection port;

FIG. 11 is an elevation view of another embodiment of a fan caseassembly for the gas turbine engine of FIG. 1 looking radially inwardfrom radially outward of the fan case assembly showing an airrecirculation duct included in the fan case assembly extends axially andcircumferentially such that an extraction port included in the airrecirculation duct is circumferentially offset from an injection portincluded in the air recirculation duct;

FIG. 12 is an elevation view of another embodiment of a fan caseassembly for the gas turbine engine of FIG. 1 looking radially inwardfrom radially outward of the fan case assembly showing an airrecirculation duct included in the fan case assembly includes extractionports spaced apart circumferentially from each other, injection portsspaced apart circumferentially from each other, and a manifold thatextends circumferentially part way about the axis between the extractionports and the injection ports so as to put the extraction ports andinjection ports in fluid communication with each other; and

FIG. 13 is an elevation view of another embodiment of a fan caseassembly for the gas turbine engine of FIG. 1 looking radially inwardfrom radially outward of the fan case assembly showing an airrecirculation duct included in the fan case assembly includes extractionports spaced apart circumferentially from each other, an injection portlocated circumferentially between the extraction ports, and a manifoldthat is in fluid communication between the extraction ports and theinjection port to feed the air directed out of the gas path by theextraction ports to the single injection port.

DETAILED DESCRIPTION OF THE DRAWINGS

For the purposes of promoting an understanding of the principles of thedisclosure, reference will now be made to a number of illustrativeembodiments illustrated in the drawings and specific language will beused to describe the same.

A fan case assembly 10 is adapted for use in a gas turbine engine 110 asshown in FIG. 1 . The gas turbine engine 110 includes a fan 112, acompressor 114, a combustor 116, and a turbine 118 as shown in FIG. 1 .The fan 112 is driven by the turbine 118 and provides thrust forpropelling an aircraft. The compressor 114 compresses and delivers airto the combustor 116. The combustor 116 mixes fuel with the compressedair received from the compressor 114 and ignites the fuel. The hot, highpressure products of the combustion reaction in the combustor 116 aredirected into the turbine 118 to cause the turbine 118 to rotate aboutan axis 11 of the gas turbine engine 110 and drive the compressor 114and the fan 112.

The fan 112 includes a fan rotor 12 and a fan case assembly 10 as shownin FIG. 1 . The fan rotor 12 has a number of fan blades 14. The fan caseassembly 10 extends circumferentially around the fan blades 14 of thefan rotor 12 such that the fan case assembly 10 is aligned axially withthe fan blades 14.

The fan case assembly 10 includes, among other components, an annularcase 20, a fan track liner 22, and an air recirculation duct 24 as shownin FIGS. 1-4 . The annular case 20 is configured to support the fantrack liner 22 at a radial position relative to a central axis 11 of thegas turbine engine 110. The fan track liner 22 extends circumferentiallyat least partway about the central axis 11 of the gas turbine engine 110and defines a portion of a gas path 18 of the gas turbine engine 110.The air recirculation duct 24 is configured to direct a portion of gasesflowing through the gas path 18 of the gas turbine engine 110 from anaft end 32 of the fan track liner 22 into the gas path 18 axiallyforward of a forward end 30 of the fan track liner 22.

The air recirculation duct 24 includes an extraction port 60, a conduit62, and an injection port 64 as shown in FIGS. 2 and 4 . In someembodiments, the ports 60, 64 and conduit 62 are integrally formed as asingle, one-piece component. In other embodiments, the ports 60, 64 andconduit 62 are individual or even several components each that arecoupled together. Both the extraction port 60 and the injection port 64are in fluid communication with the gas path 18 of the gas turbineengine 110, while the conduit 62 is in fluid communication with theextraction and injection ports 60, 64. The extraction port 60 extendsradially through an outer wall 38 of the case 20 at a location axiallyaft of the aft end 32 of the fan track liner 22. The conduit 62 extendsaxially forward from the extraction port 60 toward the forward end 30 ofthe fan track liner 22 to the injection port 64. The injection port 64extends radially inward from the conduit 62 through the outer wall 38 ofthe case 20 at a location axially forward of the forward end 30 of thefan track liner 22.

The conduit 62 is located radially outward of the outer wall 38 of theannular case 20 as shown in FIGS. 2 and 4 . The extraction port 60 andthe injection port 62 extend radially inward through the outer wall 38of the case 20 and open into the gas path 18. In this way, a portion ofgases flowing through the gas path 18 is directed from the aft end 32 ofthe fan track liner 22 radially outward outside of the case 20, axiallyforward toward the forward end 30 of the liner 22, and radially inwardback into the gas path 18 axially forward of the forward end 30 of thefan track liner 22.

In the illustrative embodiment, the fan case assembly 10 includes aplurality of air recirculation ducts 24 as shown in FIGS. 1 and 10 . Theair ducts 24 are spaced apart circumferentially about the axis 11. Thenumber of air recirculation ducts 24 may depend on the size of theengine 110 or on the stall margin improvement the engine 110 may use. Ifthe engine 110 has need for a greater stall margin improvement, thenumber of air recirculation ducts 24 may be increased and vice versa.

In the illustrative embodiment, the conduit 62 solely extends axiallybetween the extraction and injection ports 60, 64 as shown in FIG. 10 .In FIG. 10 , the air recirculation duct 24 is shown from radiallyoutward of the case 20 looking radially inward. In the illustrativeembodiment, the extraction port 60 is circumferentially aligned with theinjection port 64 so that the conduit 62 only extends in the axialdirection relative to the central axis 11 of the gas turbine engine 10.

Turning again to the fan case assembly 10, the fan case assembly 10includes the annular case 20, the fan track liner 22, the airrecirculation ducts 24, and acoustic panels 26, 28 as shown in FIGS. 2and 4 . The fan track liner 22 is formed by a number of liner segments22 in the illustrative embodiment. The acoustic panels 26, 28 arelocated forward and aft of the fan track liner 22.

Each liner segment 22 includes a forward end 30, an aft end 32 spacedapart axially from the forward end 30, and inner and outer radialsurfaces 34, 36 as shown in FIGS. 2 and 4 . The inner and outer radialsurfaces 34, 36 extend between the forward end 30 and the aft end 32.The inner radial surface 34 defines a portion of the gas path 18 of thegas turbine engine 110. The acoustic panels 26, 28 define portions ofthe gas path 18 of the gas turbine engine 110 axially forward and aft ofthe fan track liner 22 as shown in FIGS. 2 and 4 .

The liner segments 22 and the acoustic panels 26, 28 are coupled to theannular case 20 as shown in FIG. 4 . The forward acoustic panel 26 iscoupled to the annular case 20 axially forward of the liner 22. The aftacoustic panel 28 is coupled to the annular case 20 axially aft of theliner 22.

The annular case 20 includes the outer wall 38, a hook 40, and a flange42 as shown in FIGS. 2-4A. The outer wall 38 extends circumferentiallyaround the central axis 11 of the gas turbine engine 110. The hook 40extends radially inward from the outer wall 38 to support the forwardend 30 of the fan track liner 22. The flange 42 extends radially outwardfrom the outer wall 38 axially aft of the hook 40. In the illustrativeembodiment, the fan track liner 22 is coupled to the outer wall 38 nearthe aft end 32 of the fan track liner 22 with a fastener to support theaft end 32 of the fan track liner 22.

In the illustrative embodiment, the annular case 20 extends between aforward end 21 and an aft end 23 as shown in FIGS. 1, 3, and 10 . Theaft end 23 is spaced apart axially from the forward end 21.

The outer wall 38 of the case 20 has zones 54, 56, 58 that the airrecirculation duct 24 can extend through without significantlycompromising the structural integrity of the annular case 20 as shown inFIG. 3 . The first zone 54 is located axially forward of the hook 40 ofthe case 20. The second zone 56 is located axially aft of the flange 42of the case 20. The third zone 58 is located axially forward of theflange 42 of the case 20. The injection port 64 may extend through theouter wall 38 of the case 20 in the first zone 54, while the extractionport 60 may extend through the outer wall 38 of the case 20 in eitherthe second zone 56 or the third zone 58. In the illustrative embodiment,the extraction port 60 extends through the outer wall 38 of the case 20in the second zone 56.

In other embodiments, the liner 22 may be bolted to the annular case 20without the hook 40. In other embodiments, the liner 22 may be coupledto the annular case 20 with adhesive.

The hook 40 includes a radially-extending portion 44, a forward flange46, and an aft flange 48 as shown in FIGS. 3 and 4 . Theradially-extending portion 44 extends radially inward form the outerwall 38. The forward flange 46 extends axially forward away from theradially-extending portion 44 at a location radially spaced apart fromthe outer wall 38 to form a first axially opening channel 50 as shown inFIG. 3 . The aft flange 48 extends axially aft away from theradially-extending portion 44 at a location radially spaced apart fromthe outer wall 38 to form a second axially opening channel 52 as shownin FIG. 3 .

The forward flange 46 engages the forward acoustic panel 26 to supportthe forward acoustic panel 26, while the aft flange 48 engages the fantrack liner 22 to support the fan track liner 22 as shown in FIG. 4 .The acoustic panel 26 extends into the first axially opening channel 52.The forward end 30 of the fan track liner 22 extends into the secondaxially opening channel 50.

In the illustrative embodiment, the injection port 64 extends throughthe outer wall 38 of the case 20 axially forward of the forward flange46 of the hook 40 and the extraction port 60 extends through the outerwall 38 axially aft of the flange 42 as shown in FIGS. 2 and 4 . Theconduit 62 is located radially outward of the flange 42 of the annularcase 20. A terminal end 42E of the flange 42 of the annular case 20engages the conduit 62 to support the air recirculation duct 24 relativeto the annular case 20. The conduit 62 may be couple to the flange 42 insome embodiments to block the air recirculation duct 24 from movingrelative to the case 20.

The conduit 62 extends between a forward end 68 and an aft end 70 asshown in FIG. 4 . The extraction port 60 extends radially inward andaxially forward from the aft end 70 of the conduit 62 such that the aftend 70 forms a bend or curve. The injection port 62 extends radiallyinward and axially aft from the forward end 68 of the conduit 62 suchthat the forward end 68 forms a bend or curve.

The extraction port 60 has a first section 72 that extends from theconduit 62 and an opening end 74 that extends from the first section 72and opens into the gas path 18 as shown in FIGS. 4 and 4A. The openingend 74 is located between the aft end 32 of the liner 22 and a forwardend 90 of the acoustic panel 28. The first section 72 extends throughthe outer wall 38 of the case 20 axially aft of the flange 42, while theopening end 74 is axially aligned with the flange 42 radially inward ofthe outer wall 38 of the case 20.

In the illustrative embodiment, the opening end 74 extends through aportion of the acoustic liner 28 as shown in FIG. 4A. The acoustic liner28 has a notch 92 in the forward end 90 of the acoustic panel 28 for theopening end to extend through.

In the illustrative embodiment, the first section 72 of the extractionport 60 has a first cross-sectional area 72D, while the opening end 74has a second cross-sectional area 74D as shown in FIG. 4A. The secondarea 74D is greater than the first area 72D.

In some embodiments, the fan case assembly 10 may further include avalve 86 as suggested in FIG. 4A. The valve 86 may be coupled to theopening end 74 of the extraction port 60 of the air recirculation duct24. The valve 86 may be configured to vary a flow of gases through theextraction port 60.

The valve 86 may be a butterfly valve configured to change between aclosed position (represented as 86′) and an open position (representedas 86) to control the flow of gases directed out of the gas path 18 intothe air recirculation duct 24. In the closed position, the valve 86′extends across the extraction port 60 to block an opening 76 in theopening end 74 of the extraction port 60 and prevent the flow of gasesthrough the extraction port 60. In the open position, the valve 86 hasrotated about the pivot point 85 so as to be spaced apart from theopening 76 and allow the flow of gases through the extraction port 60.

In the open position, the valve 86 may be flush with the gas path 18 assuggested in FIG. 4A. In other embodiments, the valve 86 may extend intothe gas path 18 when in the open position.

The valve 86 may include a scoop 88 as suggested in FIG. 4A. The scoop88 is configured to change between a retracted position (represented as88′) and an extended position (represented as 88) to control the flow ofgases directed out of the gas path 18 into the air recirculation duct24.

In the retracted position, the scoop 88′ extends into the extractionport 60 and is flush with the gas path 18 so as not to extend into thegas path 18. In the extended position, the flap 88 has moved to extendinto the gas path 18 to direct a portion of the gases flowing throughthe gas path 18 toward the opening 76 of the extraction port 60.

In some embodiments, the scoop 88 translated radially between theretracted position and the extended position. In the illustrativeembodiment, the scoop 88 pivots about the pivot point 89 between theretracted position and the extended position.

In other embodiments, the valve 86 may be a flap configured to changebetween a closed position and an open position to control the flow ofgases directed out of the gas path 18 into the air recirculation duct24. In the closed position, the flap blocks the opening 76 of theextraction port 60 to prevent the flow of gases through the extractionport 60. The flap extends over the opening 76 to block the flow of gasesthrough the extraction port 60. In the open position, the flap is spacedapart from the opening 76 of the opening end 74 of the extraction port60 and extends into the gas path 18 to direct a portion of the gasesflowing through the gas path 18 toward the opening 76 of the extractionport 60.

The injection portion 64 has a first section 78 that extends from theconduit 62 and an opening end 80 that extends from the first section 78and opens into the gas path 18 as shown in FIG. 4 . The opening end 80is located axially forward of the hook 40 such that the opening end 80extends through a portion of the acoustic liner 26. In the illustrativeembodiment, the opening end 80 is located axially forward of the forwardflange 46 of the hook 40.

In the illustrative embodiment, the opening end 80 extends radially andaxially so that the opening end 80 is at an angle 80A relative to aradial axis 93. The angle 80A of the opening end 80 may be adjusted tochange the axial location of an opening 82 formed by the opening end 80.In the illustrative embodiment, the opening 82 is spaced apart axiallyfrom the forward flange 46 of the hook 40.

In the illustrative embodiment, the injection port 64 has across-sectional area 64D that is smaller than the area 62D of theconduit 62 as shown in FIG. 4 . The area 64D of the injection port 64may be varied to control the flow of gases injected in the gas path 18.In the illustrative embodiment, the conduit 62 extends axially at aslight angle to the axis 11 of the gas turbine engine 110 as shown inFIG. 4 .

The extraction port 60 and the injection port 64 may have an oblongcross-section as suggested in FIG. 10 . Each of the extraction port 60and the injection port 64 may extend in circumferential direction todefine the oblong cross-section. The extraction port 60 may have acircumferential width 60W and the injection port 64 may have acircumferential width 64W as shown in FIG. 10 . In some embodiments, thewidths 60W, 64W of the extraction and injection ports 60, 64 may haveequal widths. In other embodiments, one of the extraction port 60 or theinjection port 64 may have a greater width than the other.

A method of assembling and using the fan case assembly 10 may includeseveral steps. The method includes coupling the fan track liner 22 tothe annular case 20. The fan track liner 22 is coupled to the case 20 byextending the forward end 30 into the channel 52 and engaging the aftflange 48 of the hook 40 with the forward end 30 of the fan track liner22. Additionally the forward and aft acoustic panel 26, 28 are coupledto the case 20 axially forward and aft of the fan track liner 22.

The method further includes extending the extraction port 60 radiallyinward through the annular case 20 and extending the injection port 64radially inward through the annular case 20 so that the conduit 62 islocated radially outward of the annular case 20. The extraction port 60is extended through the annular case 20 axially aft of the aft end 32 ofthe fan track liner 22. The injection port 64 is extended radiallyinward through the annular case 20 axially forward of the forward end 30of the fan track liner 22.

The injection port 64 is extended through the case 20 in the first zone54. The extraction port 60 is extended through the case 20 in one of thesecond or third zones 56, 58. In the illustrative embodiment, theextraction port 60 is extended through the case 20 in the second zone56.

After the fan case assembly 10 is assembled, the method includesrecirculating gases into the gas path 18 in the fan 112 of the gasturbine engine 110. During use of the gas turbine engine 110, a portionof the gases flowing through the gas path 18 is directed out of the gaspath 18 by the extraction port 60 axially aft of the aft end 32 of thefan track liner 22. The gases flow through the opening 82 of theextraction port 60 radially outward through the case 20 axially aft ofthe flange 42 and are directed axially forward by the conduit 62. Thegases are then directed radially inward back through the case 20 andinto the gas path 18 axially forward of the forward end 30 of the fantrack liner 22.

In some embodiments, the method includes controlling the amount of gasesdirected out of the gas path 18 by the extraction port 60. The methodmay include changing the valve 86 coupled to the extraction port 60between the open and closed positions to control the gases flowingthrough the air recirculation duct 24. The method may include changingthe valve 86 to the open position to increase the flow of gases into theextraction port 60 and changing the valve 86 to the closed position toblock the flow of gases into the extraction port 60.

Another embodiment of the fan case assembly 210 in accordance with thepresent disclosure is shown in FIG. 5 . The fan case assembly 210 issubstantially similar to the fan case assembly 10 shown in FIGS. 1-4Aand described herein. Accordingly, similar reference numbers in the 200series indicate features that are common between the fan case assembly210 and the fan case assembly 10. The description of the fan caseassembly 10 is incorporated by reference to apply to the fan caseassembly 210, except in instances when it conflicts with the specificdescription and the drawings of the fan case assembly 210.

The fan case assembly 210 includes an annular case 220, a fan trackliner 222, and an air recirculation duct 224 as shown in FIG. 5 . Theannular case 220 is configured to support the fan track liner 222 at aradial position relative to the axis 11 of the gas turbine engine 110.The air recirculation duct 224 is configured to direct a portion ofgases flowing through the gas path 18 of the gas turbine engine 110 froman aft end 232 of the fan track liner 222 into the gas path 18 axiallyforward of a forward end 230 of the fan track liner 222.

The air recirculation duct 224 includes an extraction port 260, aconduit 262, and an injection port 264 as shown in FIG. 5 . Both theextraction port 260 and the injection port 264 are in fluidcommunication with the gas path 18 of the gas turbine engine 110, whilethe conduit 262 is in fluid communication with the extraction andinjection ports 260, 264. The extraction port 260 extends radiallythrough an outer wall 238 of the case 220 at a location axially aft ofthe aft end 232 of the fan track liner 222. The conduit 262 extendsaxially forward from the extraction port 260 toward the forward end 230of the fan track liner 222 to the injection port 264. The injection port264 extends radially inward from the conduit 262 through the outer wall238 of the case 220 at a location axially forward of the forward end 230of the fan track liner 222.

In the illustrative embodiment, an opening end 280 of the injection port264 extends through the outer wall 238 of the case 220 axially forwardof a hook 240 included in the case 220. The opening end 280 is locatedcloser to the hook 240 than in the embodiment of FIG. 4 because the hook240 only has a radially-extending portion 244 and an aft flange 248 asshown in FIG. 5 .

The injection portion 264 extends radially inward through the outer wall238 and extends axially aft toward the hook 240 as shown in FIG. 5 . Theopening end 280 of the injection port 264 is spaced axially forward ofthe radially-extending portion 244 of the hook 240.

In the illustrative embodiment, the opening end 280 extends radially andaxially from a first section 278 of the injection port 264 so that theopening end 280 is at an angle 280A relative to a radial axis 293. Theangle 280A of the opening end 280 is greater than the angle 80A of theinjection port 64 of the embodiment in FIGS. 1-4 . In some embodiments,the angle 280A of the opening end 280 is between about 30 and 90degrees. In some embodiments, the angle 280A of the opening end 280 isbetween about 30 and 80 degrees. In some embodiments, the angle 280A ofthe opening end 280 is between about 45 and 90 degrees. In someembodiments, the angle 280A of the opening end 280 is between about 45and 80 degrees. In some embodiments, the angle 280A of the opening end280 is between about 45 and 70 degrees.

In the illustrative embodiment, the injection port 264 has across-sectional area 264D that is smaller than the area 262D of theconduit 262 as shown in FIG. 5 . The area 264D that is also smaller thanthe area 64D of the injection port 64 of the embodiment in FIGS. 1-4 .

Another embodiment of the fan case assembly 310 in accordance with thepresent disclosure is shown in FIG. 6 . The fan case assembly 310 issubstantially similar to the fan case assembly 10 shown in FIGS. 1-4Aand described herein. Accordingly, similar reference numbers in the 300series indicate features that are common between the fan case assembly310 and the fan case assembly 10. The description of the fan caseassembly 10 is incorporated by reference to apply to the fan caseassembly 310, except in instances when it conflicts with the specificdescription and the drawings of the fan case assembly 310.

The fan case assembly 310 includes an annular case 320, a fan trackliner 322, and an air recirculation duct 324 as shown in FIG. 6 . Theannular case 320 is configured to support the fan track liner 322 at aradial position relative to the axis 11 of the gas turbine engine 110.The air recirculation duct 324 is configured to direct a portion ofgases flowing through the gas path 18 of the gas turbine engine 110 froman aft end 332 of the fan track liner 322 into the gas path 18 axiallyforward of a forward end 330 of the fan track liner 322.

The air recirculation duct 324 includes an extraction port 360, aconduit 362, and an injection port 364 as shown in FIG. 6 . Both theextraction port 360 and the injection port 364 are in fluidcommunication with the gas path 18 of the gas turbine engine 110, whilethe conduit 362 is in fluid communication with the extraction andinjection ports 360, 364. The extraction port 360 extends radiallythrough an outer wall 338 of the case 320 at a location axially aft ofthe aft end 332 of the fan track liner 322. The conduit 362 extendsaxially forward from the extraction port 360 toward the forward end 330of the fan track liner 322 to the injection port 364. The injection port364 extends radially inward from the conduit 362 through the outer wall338 of the case 320 at a location axially forward of the forward end 330of the fan track liner 322.

The conduit 362 extends between a forward end 368 and an aft end 370 asshown in FIG. 6 . The extraction port 360 extends radially inward andaxially forward from the aft end 370 of the conduit 362, while theinjection port 364 extends radially inward and axially aft from theforward end 368 of the conduit 362. The conduit 362 has a varyingcross-section moving from the forward end 368 to the aft end 370 asshown in FIG. 6 .

In the illustrative embodiment, the conduit 362 has a firstcross-sectional area 368A, 370D at the forward and aft ends 368, 370 anda second cross-sectional area 362D at a location axially between theforward and aft ends 368, 370 as shown in FIG. 6 . The area 362D is lessthan the area 368D, 370D at the forward and aft ends 368, 370. In theillustrative embodiment, the conduit 362 extends axially parallel withthe axis 11 of the gas turbine engine 110.

The conduit 362 has transition sections 369, 371 where the conduit 362transitions form the first area 368D, 370D to the second area 362D asshown in FIG. 6 . The transitions sections 369, 371 have a varyingcross-sectional area.

In the illustrative embodiment, the cross-section of the conduit 362 mayvary such that the cross-section has a variety of shapes moving from theforward end 368 to the aft end 370 of the conduit 362. The cross-sectionshape may depend on the packing of the duct 24 in the fan case assembly10.

In some embodiments, the cross-section of the conduit 362 may be oblongand extends circumferentially at least partway about the axis 11. Theopenings 376, 382 of the extraction and injection ports 360, 364 by alsohave an oblong cross-section and extend at least circumferentiallypartway about the axis 11. The cross-section of the conduit 362 mayvarying moving from the forward end 368 to the aft end 370 depending onthe packing of the duct 24 in the fan case assembly 10.

In some embodiments, the flange 342 of the case 320 includes a notch 345as suggested in FIG. 6 . The flange 342 engages conduit 362 adjacent tothe aft end 370 of the conduit 362 such that the conduit 362 extendsinto the notch 345.

Another embodiment of the fan case assembly 410 in accordance with thepresent disclosure is shown in FIG. 7 . The fan case assembly 410 issubstantially similar to the fan case assembly 10 shown in FIGS. 1-4Aand described herein. Accordingly, similar reference numbers in the 400series indicate features that are common between the fan case assembly410 and the fan case assembly 10. The description of the fan caseassembly 10 is incorporated by reference to apply to the fan caseassembly 410, except in instances when it conflicts with the specificdescription and the drawings of the fan case assembly 410.

The fan case assembly 410 includes an annular case 420, a fan trackliner 422, and an air recirculation duct 424 as shown in FIG. 7 . Theannular case 420 is configured to support the fan track liner 422 at aradial position relative to the axis 11 of the gas turbine engine 110.The air recirculation duct 424 is configured to direct a portion ofgases flowing through the gas path 18 of the gas turbine engine 110 froman aft end 432 of the fan track liner 422 into the gas path 18 axiallyforward of a forward end 430 of the fan track liner 422.

The air recirculation duct 424 includes an extraction port 460, aconduit 462, and an injection port 464 as shown in FIG. 7 . Both theextraction port 460 and the injection port 464 are in fluidcommunication with the gas path 18 of the gas turbine engine 110, whilethe conduit 462 is in fluid communication with the extraction andinjection ports 460, 464. The extraction port 460 extends radiallythrough an outer wall 438 of the case 420 at a location axially aft ofthe aft end 432 of the fan track liner 422. The conduit 462 extendsaxially forward from the extraction port 460 toward the forward end 430of the fan track liner 422 to the injection port 464. The injection port464 extends radially inward from the conduit 462 through the outer wall438 of the case 420 at a location axially forward of the forward end 430of the fan track liner 422. In the illustrative embodiment, the conduit462 extends axially parallel with the outer wall 438 of the annular case420.

The annular case 420 includes the outer wall 438, a hook 440, and aflange 442 as shown in FIG. 7 . The outer wall 438 extendscircumferentially around the central axis 11 of the gas turbine engine110. The hook 440 extends radially inward from the outer wall 438 tosupport the forward end 430 of the fan track liner 422. The flange 442extends radially outward from the outer wall 438 axially aft of the hook440.

In the illustrative embodiment, the extraction port 460 extends throughthe outer wall 438 axially forward of the flange 442 instead of axiallyaft of the flange 442 like in the embodiments of FIGS. 1-6 . Theextraction port 460 extends radially inward and axially aft from an aftend 470 of the conduit 462 such that the aft end 470 forms a bend orcurve. However, because the extraction port 460 extends axially aft, thebend of the aft end 470 of the conduit 462 bends at a larger angel thanin the embodiments of FIGS. 1-6 .

The extraction port 460 has a first section 472 that extends from theconduit 462 and an opening end 474 that extends from the first section72 and opens into the gas path 18 as shown in FIG. 7 . The opening end474 is located between the aft end 432 of the liner 422 and a forwardend of the acoustic panel 428.

The opening end 474 is located axially forward of the flange 442 and aforward end 490 of the acoustic liner 428 as shown in FIG. 7 . Theopening end 474 is spaced apart from the forward end 490 of the acousticliner 428 such that the extraction port 460 does not extend through aportion of the acoustic liner 428.

In the illustrative embodiment, the extraction port 460 has a differentshape than embodiments of FIGS. 1-6 . The extraction port 460 has avariable cross-sectional area. The opening end 474 of has an opening 476with a cross-sectional area 476A that is greater than the area 462D ofthe conduit 462.

A method of assembling and using the fan case assembly 410 may includeseveral steps. The method includes coupling the fan track liner 422 tothe annular case 420, extending the extraction port 460 radially inwardthrough the annular case 420, and extending the injection port 464radially inward through the annular case 420 so that the conduit islocated radially outward of the annular case. The extraction port 460 isextended through the annular case 420 axially aft of the aft end 432 ofthe fan track liner 422 axially forward of the flange 442. The injectionport 464 is extended radially inward through the annular case 420axially forward of the forward end 430 of the fan track liner 422.

Another embodiment of the fan case assembly 510 in accordance with thepresent disclosure is shown in FIG. 8 . The fan case assembly 510 issubstantially similar to the fan case assembly 10 shown in FIGS. 1-4Aand described herein. Accordingly, similar reference numbers in the 500series indicate features that are common between the fan case assembly510 and the fan case assembly 10. The description of the fan caseassembly 10 is incorporated by reference to apply to the fan caseassembly 510, except in instances when it conflicts with the specificdescription and the drawings of the fan case assembly 510.

The fan case assembly 510 includes an annular case 520, a fan trackliner 522, and an air recirculation duct 524 as shown in FIG. 8 . Theannular case 520 is configured to support the fan track liner 522 at aradial position relative to the axis 11 of the gas turbine engine 110.The air recirculation duct 524 is configured to direct a portion ofgases flowing through the gas path 18 of the gas turbine engine 110 froman aft end 532 of the fan track liner 522 into the gas path 18 axiallyforward of a forward end 530 of the fan track liner 522.

The air recirculation duct 524 includes an extraction port 560, aconduit 562, and an injection port 564 as shown in FIG. 8 . Both theextraction port 560 and the injection port 564 are in fluidcommunication with the gas path 18 of the gas turbine engine 110, whilethe conduit 562 is in fluid communication with the extraction andinjection ports 560, 564. The extraction port 560 extends radiallythrough an outer wall 538 of the case 520 at a location axially aft ofthe aft end 532 of the fan track liner 522. The conduit 562 extendsaxially forward from the extraction port 560 toward the forward end 530of the fan track liner 522 to the injection port 564. The injection port564 extends radially inward from the conduit 562 through the outer wall538 of the case 520 at a location axially forward of the forward end 530of the fan track liner 522.

The annular case 520 includes the outer wall 538, a hook 540, and aflange 542 as shown in FIG. 8 . The outer wall 538 extendscircumferentially around the central axis 11 of the gas turbine engine110. The hook 540 is configured to support the forward end 530 of thefan track liner 522. The flange 542 extends radially outward from theouter wall 538 axially aft of the hook 540. In the illustrativeembodiment, portions of the outer wall 538 define a portion of the gaspath 18 of the gas turbine engine 110 as shown in FIG. 8 .

The fan case assembly 510 does not include acoustic panels like in theembodiments of FIGS. 1-7 . Rather, the outer wall 538 forms a portion ofthe gas path 18 as shown in FIG. 8 . The outer wall 538 includes aforward section 594, an intermediate section 596, and an aft section 598as shown in FIG. 8 . The hook 540 is formed between the forward section594 and the intermediate section 596 of the outer wall 538. The aftsection 598 that extends axially aft from the intermediate section 596.

The hook 540 includes a radially-extending portion 544 and an aft flange548 as shown in FIG. 8 . The radially-extending portion 544 extendsradially inward form the intermediate section 596 of the outer wall 38to the forward section 594 of the outer wall 538. The aft flange 548extends axially aft away from the radially-extending portion 544 at alocation radially spaced apart from the intermediate portion 596 of theouter wall 538 to form an axially opening channel 552. In theillustrative embodiment, the aft flange 548 is flush with the forwardsection 594 of the outer wall 538 so as to form a portion of the gaspath 18 as shown in FIG. 8 .

In the illustrative embodiment, the flange 548 of the case 520 extendsfrom the outer wall 538 at the intersection of the intermediate section596 and the aft section 598 of the outer wall 538. The aft section 598has a radially-extending portion 597 and an axially-extending portion599 as shown in FIG. 8 . The radially-extending portion 597 extendsradially inward from the intermediate section 596 toward the gas path 18and the axially-extending portion 599 extends axially aft form theradially-extending portion 597. The axially-extending portion 599 formsa portion of the gas path 18.

The conduit 562 extends between a forward end 568 and an aft end 570 asshown in FIG. 8 . The extraction port 560 extends radially inward andaxially aft from the aft end 570 of the conduit 562 such that the aftend 570 forms a bend or curve. The injection port 564 extends radiallyinward and from the forward end 568 of the conduit 562 such that theforward end 568 forms a bend or curve.

The extraction port 560 has a first section 572 that extends from theconduit 562 and an opening end 574 that extends from the first section572 and opens into the gas path 18 as shown in FIG. 8 . The opening end574 is located between the aft end 532 of the liner 522 and theradially-extending portion 597. The first section 572 extends throughthe outer wall 538 of the case 520 axially forward of the flange 542 inthe illustrative embodiment.

In the illustrative embodiment, the first section 572 of the extractionport 560 has a first cross-sectional area 572D, while the opening end574 flares out so that an opening 576 of the opening end 574 has alarger area 576A than the first area 572D. The area 576A of the opening576 is greater than the area 562D as shown in FIG. 8 .

The injection port 564 extends radially inward from the forward end 568of the conduit 562 as shown in FIG. 8 . The injection port 564 does notextend axially such that the injection port 564 is parallel to a radialaxis 593. The injection port 564 extends through the forward section 594of the outer wall 538 axially forward of the radially-extending portion544. The opening 582 of the injection port 564 is flush with the forwardsection 594 of the outer wall 538. In the illustrative embodiment, theinjection port 564 has a cross-sectional area 564D that is equal to thearea 562D of the conduit 562 as shown in FIG. 8 .

Another embodiment of the fan case assembly 610 in accordance with thepresent disclosure is shown in FIG. 9 . The fan case assembly 610 issubstantially similar to the fan case assembly 10 shown in FIGS. 1-4Aand described herein. Accordingly, similar reference numbers in the 600series indicate features that are common between the fan case assembly610 and the fan case assembly 10. The description of the fan caseassembly 10 is incorporated by reference to apply to the fan caseassembly 610, except in instances when it conflicts with the specificdescription and the drawings of the fan case assembly 610.

The fan case assembly 610 includes an annular case 620, a fan trackliner 622, and an air recirculation conduit 624 as shown in FIG. 9 . Theannular case 620 is configured to support the fan track liner 622 at aradial position relative to the axis 11 of the gas turbine engine 110.The air recirculation conduit 624 is configured to direct a portion ofgases flowing through the gas path 18 of the gas turbine engine 110 froman aft end 632 of the fan track liner 622 into the gas path 18 axiallyforward of a forward end 630 of the fan track liner 622.

The air recirculation conduit 624 includes an extraction port 660, aconduit 662, and an injection port 664 as shown in FIG. 9 . Both theextraction port 660 and the injection port 664 are in fluidcommunication with the gas path 18 of the gas turbine engine 110, whilethe conduit 662 is in fluid communication with the extraction andinjection ports 660, 664. The extraction port 660 extends radiallythrough an outer wall 638 of the case 620 at a location axially aft ofthe aft end 632 of the fan track liner 622. The conduit 662 extendsaxially forward from the extraction port 660 toward the forward end 630of the fan track liner 622 to the injection port 664. The injection port664 extends radially inward from the conduit 662 through the outer wall638 of the case 620 at a location axially forward of the forward end 630of the fan track liner 622.

The annular case 620 includes the outer wall 638, a hook 640, and aflange 642 as shown in FIG. 9 . The outer wall 638 extendscircumferentially around the central axis 11 of the gas turbine engine110. The hook 640 is configured to support the forward end 630 of thefan track liner 622. The flange 642 extends radially outward from theouter wall 638 axially aft of the hook 640. In the illustrativeembodiment, portions of the outer wall 638 define a portion of the gaspath 18 of the gas turbine engine 110 as shown in FIG. 9 .

The outer wall 638 includes a forward section 694, an intermediatesection 696, and an aft section 698 as shown in FIG. 9 . The hook 640 isformed between the forward section 694 and the intermediate section 696of the outer wall 638. The aft section 698 that extends axially aft fromthe intermediate section 696. The air recirculation conduit 624 extendsaxially through the flange 642 and through the aft section 698 of theouter wall 638 as shown in FIG. 8 .

In the illustrative embodiment, the flange 642 of the case 620 extendsfrom the outer wall 638 at the intersection of the intermediate section696 and the aft section 698 of the outer wall 638 as shown in FIG. 9 .The aft section 698 has a radially-extending portion 697 and anaxially-extending portion 699 as shown in FIG. 9 . Theradially-extending portion 697 extends radially inward from theintermediate section 696 toward the gas path 18 and theaxially-extending portion 699 extends axially aft form theradially-extending portion 697. The axially-extending portion 699 formsa portion of the gas path 18.

The conduit 662 extends between a forward end 668 and an aft end 670 asshown in FIG. 9 . The extraction port 660 extends radially inward andaxially forward from the aft end 670 of the conduit 662 such that theaft end 670 forms a bend or curve. The injection port 664 extendsradially inward and from the forward end 668 of the conduit 662 suchthat the forward end 668 forms a bend or curve.

In the illustrative embodiment, the conduit 662 extends axially throughthe flange 642 such that the aft end 670 is located axially aft of theflange 642 of the outer wall 538. The flange 642 is shaped to include anotch 635 and the conduit 662 extends through the notch 635 in theflange 642 as shown in FIG. 9 . The conduit 662 is parallel with theintermediate section 696 in the illustrative embodiment.

The conduit 662 bends axially aft of the flange 642 so that theextraction port 660 extends radially inward and axially forward throughthe aft section 698 of the outer wall 638. The extraction port 660extends radially inward and axially forward through theradially-extending portion 697 of the aft section 598 in theillustrative embodiment.

The extraction port 660 has a first section 672 that extends from theconduit 662 and an opening end 674 that extends from the first section672 and opens into the gas path 18 as shown in FIG. 9 . The opening end674 is located between the aft end 632 of the liner 622 and theradially-extending portion 697. The first section 672 extends throughthe outer wall 638 of the case 620 axially forward of the flange 642 inthe illustrative embodiment.

In the illustrative embodiment, the first section 672 of the extractionport 660 has a first cross-sectional area 672D, while the opening end674 flares out so that an opening 676 of the opening end 674 has alarger area 676A than the first area 672D.

A method of assembling and using the fan case assembly 610 may includeseveral steps. The method includes coupling the fan track liner 622 tothe annular case 620, extending the extraction port 660 radially inwardthrough the annular case 620, and extending the injection port 664radially inward through the annular case 620 so that the conduit islocated radially outward of the annular case. The extraction port 660 isextended through the flange 642 and the radially-extending portion 697so that the extraction port 660 is aft of the aft end 632 of the fantrack liner 622. The injection port 664 is extended radially inwardthrough the annular case 620 axially forward of the forward end 630 ofthe fan track liner 622.

Another embodiment of the fan case assembly 710 in accordance with thepresent disclosure is shown in FIG. 11 . The fan case assembly 710 issubstantially similar to the fan case assembly 10 shown in FIGS. 1-4Aand described herein. Accordingly, similar reference numbers in the 700series indicate features that are common between the fan case assembly710 and the fan case assembly 10. The description of the fan caseassembly 10 is incorporated by reference to apply to the fan caseassembly 710, except in instances when it conflicts with the specificdescription and the drawings of the fan case assembly 710.

The fan case assembly 710 includes an annular case 720 and an airrecirculation duct 724 as shown in FIG. 11 . The annular case 720 isconfigured to support the fan track liner at a radial position relativeto the axis 11 of the gas turbine engine 110. The air recirculation duct724 is configured to direct a portion of gases flowing through the gaspath 18 of the gas turbine engine 110 from an aft end of the fan trackliner into the gas path 18 axially forward of a forward end of the fantrack liner.

The air recirculation duct 724 includes an extraction port 760, aconduit 762, and an injection port 764 as shown in FIG. 11 . Both theextraction port 760 and the injection port 764 are in fluidcommunication with the gas path 18 of the gas turbine engine 110, whilethe conduit 762 is in fluid communication with the extraction andinjection ports 760, 764. The extraction port 760 extends radiallythrough an outer wall 738 of the case 720 at a location axially aft ofthe aft end of the fan track liner. The conduit 762 extends axiallyforward from the extraction port 760 toward the forward end of the fantrack liner to the injection port 764. The injection port 764 extendsradially inward from the conduit 762 through the outer wall 738 of thecase 720 at a location axially forward of the forward end of the fantrack liner.

In the illustrative embodiment, the injection port 764 iscircumferentially offset from the extraction port 760 as shown in FIG.11 . As such, the conduit 762 extends axially and circumferentially fromthe extraction port 760 to the injection port 764.

In the illustrative embodiment, the injection port 764 extends throughthe outer wall 738 of the case 720 axially forward of the hook 740 andthe extraction port 760 extends through the outer wall 738 axially aftof the flange 742 as shown in FIGS. 2 and 4 . The conduit 762 is locatedradially outward of the flange 742 of the annular case 720.

Another embodiment of the fan case assembly 810 in accordance with thepresent disclosure is shown in FIG. 12 . The fan case assembly 810 issubstantially similar to the fan case assembly 10 shown in FIGS. 1-4Aand described herein. Accordingly, similar reference numbers in the 800series indicate features that are common between the fan case assembly810 and the fan case assembly 10. The description of the fan caseassembly 10 is incorporated by reference to apply to the fan caseassembly 810, except in instances when it conflicts with the specificdescription and the drawings of the fan case assembly 810.

The fan case assembly 810 includes an annular case 820 and an airrecirculation duct 824 as shown in FIG. 12 . The annular case 820 isconfigured to support the fan track liner at a radial position relativeto the axis 11 of the gas turbine engine 110. The air recirculation duct824 includes extraction ports 860A, 860B, a manifold 862, and injectionports 864A, 864B as shown in FIG. 12 .

The extraction ports 860A, 860B and the injection ports 864A, 864B arein fluid communication with the gas path 18 of the gas turbine engine110, while the manifold 862 is in fluid communication with theextraction and injection ports 860A, 860B, 864A, 864B. The manifold 862extends between the extraction ports 860A, 860B and injection ports864A, 864B to put them all in fluid communication with each other. Inthis way, the portion of gases directed out of the gas path by one ofthe extraction ports 860A, 860B may flow to either one of the injectionports 864A, 864B.

The extraction ports 860A, 860B extend radially through an outer wall838 of the case 820 at a location axially aft of the aft end of the fantrack liner. The injection ports 864A, 864B extend radially inwardthrough the outer wall 838 of the case 820 at a location axially forwardof the forward end of the fan track liner. The second extraction port860B is spaced apart circumferentially from the first extraction port860A, and the second injection port 864B is spaced apartcircumferentially from the first injection port 864A as shown in FIG. 12.

The first extraction port 860A is circumferentially aligned with thefirst injection port 864A, while the second extraction port 860B iscircumferentially aligned with the second injection port 864B as shownin FIG. 12 . The manifold extend circumferentially about the axis 11between the ports 860A, 860B, 864A, 864B.

The manifold 862 includes a first conduit 863, a second conduit 865, andan interconnecting conduit 867 as shown in FIG. 12 . The first conduit863 extends axially forward from the first extraction port 860A towardthe forward end of the fan track liner to the first injection port 864A.The second conduit 865 extends axially forward from the secondextraction port 860B toward the forward end of the fan track liner tothe second injection port 864B. The interconnecting conduit 867 extendscircumferentially between the first and second conduits 863, 865.

In the illustrative embodiment, the interconnecting conduit 867 extendsat least circumferentially partway about the axis 11 between the firstand second conduits 863, 865 so that the gases that enter in the airrecirculation duct 824 may flow to either one of the first or secondinjection ports 864A, 864B. For example, of the gases that flow into thefirst extraction port 860A, a portion of the gases may flow through thefirst conduit 863 to the first injection port 864A, while anotherportion of the gases may flow through the first conduit 863, theinterconnecting conduit 867, and the second conduit 865 to the secondinjection port 864B. Similarly, of the gases that flow into the secondextraction port 860B, a portion of the gases may flow through the secondconduit 865 to the second injection port 864B, while another portion ofthe gases may flow through the second conduit 865, the interconnectingconduit 867, and the first conduit 863 to the first injection port 864A.

Another embodiment of the fan case assembly 910 in accordance with thepresent disclosure is shown in FIG. 13 . The fan case assembly 910 issubstantially similar to the fan case assembly 10 shown in FIGS. 1-4Aand described herein. Accordingly, similar reference numbers in the 900series indicate features that are common between the fan case assembly910 and the fan case assembly 10. The description of the fan caseassembly 10 is incorporated by reference to apply to the fan caseassembly 910, except in instances when it conflicts with the specificdescription and the drawings of the fan case assembly 910.

The fan case assembly 910 includes an annular case 920 and an airrecirculation duct 924 as shown in FIG. 13 . The annular case 920 isconfigured to support the fan track liner at a radial position relativeto the axis 11 of the gas turbine engine 110. The air recirculation duct924 includes extraction ports 960A, 960B, a manifold 962, and aninjection port 964 as shown in FIG. 12 .

The extraction ports 960A, 960B and the injection port 964 are in fluidcommunication with the gas path 18 of the gas turbine engine 110, whilethe manifold 962 is in fluid communication with the extraction ports960A, 960B and the injection port 964. The manifold 962 extends betweenthe extraction ports 960A, 960B and the injection port 964 so that thetwo extraction ports 960A, 960B feed the single injection port 964.

In the illustrative embodiment, the air recirculation duct 924 includestwo extraction ports 960A, 960B that feed the one injection port 964 asshown in FIG. 13 . The second extraction port 960B is spaced apartcircumferentially from the first extraction port 960B. In otherembodiments, the air recirculation duct 924 may have more than twoextraction ports 960A, 960B that feed the one injection port 964.

In the illustrative embodiment, the injection port 964 iscircumferentially between the first extraction port 960A and the secondextraction port 960B as shown in FIG. 13 . The manifold 962 extendsbetween the injection port 964 and the first and second extraction ports960A, 9608.

The manifold 962 includes a central duct 963 and a plurality of conduits965, 967, 969 that extend from the central duct 963 to one of the ports960A, 960B, 964 as shown in FIG. 13 . The central duct 963 is arrangedaxially between the extraction ports 960A, 960B and the injection port964. The first conduit 965 extends axially forward from the firstextraction port 960A to the central duct 963. The second conduit 967extends axially forward from the second extraction port 960B to thecentral duct 963. The third conduit 969 extends axially aft from theinjection port 964 to the central duct 963.

A portion of the gases from the gas path 18 flows into the extractionports 960A, 960B and the corresponding conduits 965, 967 direct theportion of gases to the central duct 963. Then the combined flows areflow through the third conduit 969 to the injection port 964. Thecombined flow is then injected back into the gas path 18 axially forwardof the forward end of the fan track liner.

The present application relates to tip injection or air recirculation inthe fan 112 in the gas turbine engine 110. Typically, tip injection maybe used in a compressor to increase stall margin of the compressor.However, integrating air recirculation into the fan 112 causes somedesign difficulties because the fan 112 has complex systems for fanblade containment that may be problematic to work around.

In the illustrative embodiment, the fan case assembly 10 has an airrecirculation duct 24 integrated for the tip injection through specificzones 54, 56, 58 of the fan case 20, which would permit the case 20 toremain structurally sound for containing the blades 14. The containmenthook 40 located in front of the rotor may allow for injection ahead ofthe hook 40. Injection ahead of the hook 40 protects the injection port64. Likewise, the flange 42 may provide some shielding for theextraction port 60 at the aft end 32 of the fan track liner 22. Thisavoids holes in the main containment region of the case 20 where strainsare high, while still allowing for incorporation of tip injectionrecirculation.

The case 20 may allow the air recirculation duct 24 to be installedthrough the containment case 20 without the loss of its structuralintegrity. To provide sufficient recirculation flow without disruptingaspects of the containment system functionality, off-takes, orextraction ports 60, may be located behind the fan track liner 22 by theflange 42 and connected via the conduit 62 to the injection ports 64ahead of the containment hook 40.

In the illustrative embodiment, the fan track liner 22 extends toaccommodate the extent of high energy ice shedding. The fan track liner22 includes an extent of margin before the rear acoustic panel 28begins. This usually includes a gap that is filled with sealant;however, the extraction port 60 extends through the case 20 and opens atthis location. With this particular configuration, the port 60 might beforward or aft of the flange 42 depending on the particular engine size,fan case design, and its strains predicted during fan blade outsimulation.

In some embodiments, the aft end 32 of the fan track liner 22 may havecastellated regions to allow for the extraction ports 60 to be forwardof the flange 42. In other embodiments, the forward end 90 of theacoustic panel 28 may have cut sections out between its fasteners sothat the port 64 is aft of the flange 42. This would allow the conduit62 to be run to the injection port 64 radially outward of the case 20.

The particular size and count of the air recirculation ducts 24 may betailored to a specific fan size and stall margin improvement for the gasturbine engine 110. This is due to the fact that changes inrecirculation flow can modify the stall margin and this is correlatedwith the flow of the fan overall. Therefore, larger ports or a highercount may be used for different sized fans.

In the illustrative embodiment, the extraction port 60 is flush to flowpath 18. The extraction port 60 also includes a valve 86. The valve 86includes a scoop or flap 88 to increase flow into the extraction port60. The flap 86 may extend across the opening 76 to block flow whenadditional stall is not desired and efficiency debit is to be minimized.The flap 88 could pivot from a closed position to an open position tohelp recover more flow/pressure into the channel-way. In someembodiments, the valve 86 may be a butterfly valve or similar to blockflow into the extraction port when system is not on.

In some embodiments, the air recirculation ducts 24 may be aligned withcut-outs in the panel. One may have 8-off rear acoustic panels with anextraction port in the middle of each and then have 4-off front acousticpanels, each with two injection passages through them. Alternatively,there could be 6-off rear acoustic panels with two cut-outs forextraction each and 4-off with three passages for injection on each.Alternatively there may be 12-off extraction ports and 6-off injectionports, as suggested by FIG. 13 .

While the injection may not be equally distributed, it does make sensefor packaging to use repeating patterns in the liner definitions.Additionally, it may be beneficial for the flange to be scalloped toensure there is adequate support to bolt brackets in order to hold theduct 24. The duct 24 may be 1.5 inches in diameter or so to reducepressure losses through it but manifolds may be used to transfer from acircumferentially wide and axially narrow port to a straight circularpipe and then back to the injector which would be axially narrow andthen circumferentially wide.

The position of the hook for example may be a percentage of the bladeaxial chord while the tip injection would be more forward of the rotorleading edge than typically used for tip injection, but still within agreater percentage of the blade axial chord. If the hook was madeshorter (by use of tabs to attach the forward flange of the fan trackliner) and no forward projection 46 was included at the forward acousticpanel then the distance from injection to rotor leading edge can beminimized. Additionally, the example cross-section uses a high-airfoilcount rotor, which for a lower count would have a longer chord andtherefore the distance from injection to rotor leading edge would bereduced as fraction of the blade axial chord.

For small and medium engines, there are particular regions of the fancase 20 that would be more conducive to creating holes for tip injectionports and passages. These are generally just ahead of the containmenthook 40 and around the flange 42. Therefore, for small and mediumengines, holes for the extraction port 60 may be past 75 percent betweenthe hook 40 and the flange 42. Likewise, the first 25 percent of thecase 20 would be acceptable for making a passage for the injection port64.

The resulting fan case assembly 10 provides effective integration of asystem capable of improving stall margin by incorporating extraction andinjection ports 60, 64 in zones that would permit passage through thecase 20 without significantly compromising the integrity of thecontainment function of the case 20. In some embodiments, circularcross-section duct 24 may be used. In other embodiments, oval-shapedcircumferentially wide but radially short ducts 24 may be.

While the disclosure has been illustrated and described in detail in theforegoing drawings and description, the same is to be considered asexemplary and not restrictive in character, it being understood thatonly illustrative embodiments thereof have been shown and described andthat all changes and modifications that come within the spirit of thedisclosure are desired to be protected.

1. A fan case assembly adapted for use with a gas turbine engine, thefan case assembly comprising a fan track liner that extendscircumferentially at least partway about a central axis of the gasturbine engine, the fan track liner including a forward end, an aft endspaced apart axially from the forward end, and an inner radial surfacethat extends between the forward end and the aft end to define a gaspath of the gas turbine engine, an annular case configured to supportthe fan track liner at a radial position relative to the central axis,the annular case including an outer wall that extends circumferentiallyaround the central axis of the gas turbine engine and a hook thatextends radially inward from the outer wall to support the forward endof the fan track liner, the outer wall including an outer radialsurface, and a discrete air recirculation duct configured to direct aportion of gases flowing through the gas path of the gas turbine enginefrom the aft end of the fan track liner into the gas path axiallyforward of the forward end of the fan track liner, the air recirculationduct including an extraction port in fluid communication with the gaspath of the gas turbine engine that extends radially through the entireouter wall at a location axially aft of the aft end of the fan trackliner, a conduit in fluid communication with the extraction port, theconduit extends axially forward from the extraction port toward theforward end of the fan track liner, the conduit located radially outwardof the outer wall such that the gases flowing through the conduit arenot exposed to the outer radial surface of the outer wall, and aninjection port in fluid communication with the gas path of the gasturbine engine and the conduit, the injection port extends radiallyinward from the conduit through the entire outer wall at a locationaxially forward of the forward end of the fan track liner and the hookof the annular case.
 2. The fan case assembly of claim 1, wherein theannular case further includes a flange that extends radially outwardfrom the outer wall axially aft of the hook and the extraction port ofthe air recirculation duct extends through the outer wall axially aft ofthe flange.
 3. The fan case assembly of claim 2, wherein the conduit ofthe air recirculation duct is located radially outward of the flange ofthe annular case and the flange of the annular case engages the conduitto support the air recirculation duct relative to the annular case. 4.The fan case assembly of claim 3, wherein the conduit has a forward endand an aft end spaced apart axially from the forward end, the conduithas a first cross-section at the forward and aft ends of the conduit anda second cross-section at a location axially between the forward and aftends of the conduit, and the second cross-section is different than thefirst cross-section.
 5. The fan case assembly of claim 3, wherein theinjection port extends radially inward and axially aft so that theinjection port extends at an angle relative to a radial axis thatextends radially relative to the central axis.
 6. The fan case assemblyof claim 2, wherein the conduit of the air recirculation duct extendsthrough a passage formed in the flange of the annular case so that theflange supports the air recirculation duct radially relative to theannular case.
 7. The fan case assembly of claim 1, wherein the annularcase further includes a flange that extends radially outward from theouter wall axially aft of the hook and the extraction port of the airrecirculation duct extends through the outer wall axially forward of theflange.
 8. The fan case assembly of claim 7, wherein the extraction portextends radially inward and axially aft.
 9. The fan case assembly ofclaim 8, wherein the extraction port has a first section that extendsfrom the conduit and an opening end that extends from the first section,the opening end of the extraction port forms an opening having a firstarea, and the first section has a second area that is smaller than thefirst area.
 10. The fan case assembly of claim 1, further comprising avalve coupled to the extraction port of the air recirculation duct thatis configured to vary a flow of gases through the extraction port. 11.The fan case assembly of claim 10, wherein the valve is configured tochange between a closed position in which the valve blocks an opening ofthe extraction port to prevent the flow of gases through the extractionport and an open position in which the valve is spaced apart from theopening of the extraction port and a portion of the valve extends intothe gas path to direct a portion of the flow of gases flowing throughthe gas path toward the opening of the extraction port.
 12. A fan caseassembly adapted for use in a gas turbine engine, the fan case assemblycomprising a fan track liner that extends circumferentially at leastpartway about a central axis of the gas turbine engine, the fan trackliner including a forward end, an aft end spaced apart axially from theforward end, and an inner radial surface that extends between theforward end and the aft end to define a gas path of the gas turbineengine, an annular case coupled with the fan track liner to support thefan track liner radially in the gas turbine engine, and an airrecirculation duct including an extraction port in fluid communicationwith the gas path of the gas turbine engine that extends radiallythrough the annular case at a location axially aft of the aft end of thefan track liner, a conduit that extends axially from the extraction portradially outward of the annular case, and an injection port in fluidcommunication with the gas path of the gas turbine engine that extendsradially from the conduit through the annular case at a location axiallyforward of the forward end of the fan track liner, wherein the annularcase includes an outer wall that extends circumferentially around thecentral axis of the gas turbine engine, the outer wall formed to definea discrete aft hole extending radially through the entire outer wall anda discrete forward hole extending radially through the entire outer wallat a location axially forward of the discrete aft hole, wherein theextraction port extends through the discrete aft hole and the injectionport extends through the discrete forward hole.
 13. The fan caseassembly of claim 12, wherein the annular case includes a hook thatextends radially inward from the outer wall and a flange that extendsradially outward from the outer wall axially aft of the hook, andwherein the extraction port of the air recirculation duct extendsthrough the outer wall axially aft of the flange.
 14. The fan caseassembly of claim 13, wherein the conduit of the air recirculation ductis located radially outward of the flange of the annular case and theflange of the annular case engages the conduit.
 15. The fan caseassembly of claim 13, wherein the conduit of the air recirculation ductextends through the flange of the annular case.
 16. The fan caseassembly of claim 12, wherein the annular case includes a hook thatextends radially inward from the outer wall and a flange that extendsradially outward from the outer wall axially aft of the hook, andwherein the extraction port of the air recirculation duct extendsthrough the outer wall axially forward of the flange.
 17. The fan caseassembly of claim 12, further comprising a valve coupled to theextraction port of the air recirculation duct that is configured to varya flow of gases through the extraction port.
 18. A method comprisingproviding an annular case that extends around a central axis includingan outer wall that extends circumferentially and is formed to define adiscrete aft hole extending radially through the entire outer wall and adiscrete forward hole extending radially through the entire outer wallat a location axially forward of the discrete aft hole, a fan trackliner that extends circumferentially at least partway about the centralaxis, and an air recirculation duct that includes an extraction port, aninjection port, and a conduit that extends between and interconnects theextraction port and the injection port, coupling the fan track liner tothe annular case, extending the extraction port radially inward throughthe discrete aft hole of the outer wall of the annular case axially aftof an aft end of the fan track liner, and extending the injection portradially inward through the discrete forward hole of the outer wall ofthe annular case axially forward of a forward end of the fan track linerso that the conduit is located radially outward of the annular case. 19.The method of claim 18, wherein the annular case includes a hook thatextends radially inward from the outer wall and a flange that extendsradially outward from the outer wall axially aft of the hook, andwherein the extraction port of the air recirculation duct extendsthrough the outer wall axially aft of the flange.
 20. The method ofclaim 18, wherein the annular case includes a hook that extends radiallyinward from the outer wall and a flange that extends radially outwardfrom the outer wall axially aft of the hook, and wherein the extractionport of the air recirculation duct extends through the outer wallaxially forward of the flange.